Casing layer for polyurethane-covered and polyurea-covered golf balls

ABSTRACT

This invention is related to multi-layer golf balls having at least one layer containing a neutralized high acid ionomer linked to a grafted metallocene copolymer, where the golf balls exhibit improved performance characteristics and properties.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/361,687, filed Jan. 29, 2009, now pending, the entire disclosure ofwhich is incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to an improved casing layer for multilayergolf balls. In particular, the present invention relates to partiallyand highly neutralized high acid ionomers for use as a casing layer in agolf ball with a thin and relatively soft cover. The partially andhighly neutralized high acid ionomers are reacted with a maleicanhydride grafted metallocene copolymer to form a material suitable foruse in a golf ball layer.

BACKGROUND OF THE INVENTION

Conventional golf balls can be divided into two general classes: solidand wound. Solid golf balls include one-piece, two-piece (i.e., solidcore and a cover), and multi-layer (i.e., solid core of one or morelayers and/or a cover of one or more layers) golf balls. Wound golfballs typically include a solid, hollow, or fluid-filled center,surrounded by a tensioned elastomeric material, and a cover. Over theyears, golf ball manufacturers have attempted, over the years, tomanipulate the compositions of both the core and cover materials inorder to satisfy the performance needs of skilled and recreationalgolfers. Golf ball performance can be judged by a wide spectrum ofcharacteristics including resilience, durability, spin, and “feel” ofgolf balls. When formulating a composition for a golf ball, each elementmust be balanced to produce specific characteristics.

The combination of the solid core and ionomeric cover materials providea ball that is durable and abrasion resistant. However, because thesematerials are rigid, solid balls can have a hard “feel” when struck witha club. Also, due to their construction, these balls tend to have arelatively lower spin rate and higher initial velocity, which canprovide greater distance and increased accuracy off the tee but lesscontrol for greenside play.

Recently, manufacturers have investigated the use of alternativepolymers, such as polyurethane, for use as golf ball covers. Forexample, U.S. Pat. No. 6,132,324, incorporated herein by reference,discloses a method of making a golf ball having a polyurethane cover.Polyurethanes have been recognized as useful materials for golf ballssince about 1960. Polyurethane compositions are the product of areaction between a curing agent and a polyurethane prepolymer, which isitself a product formed by a reaction between a polyol and anisocyanate.

The first commercially successful polyurethane covered golf ball was theTitleist Professional ball, first released in 1993. Subsequently, theTitleist Pro V1 ball was introduced successfully in 2000 with a solidresilient polybutadiene core, a hard ionomer casing and a polyurethanecover. The Pro V1 ball provided both professional and amateur playerswith long distance off of drivers and control for greenside play.However, further improvements in ball properties can be anticipated byvarying the composition of the ionomer layer.

The present invention relates to a further attempt to provide a ballwith equal or improved properties compared to the Pro V1 achievedthrough the use of new compositions for use in golf ball layers.

SUMMARY OF THE INVENTION

The present invention is directed to a golf ball including a core, acover, and a layer disposed between the core and cover, wherein thecover includes polyurea, and wherein the layer disposed between the coreand cover further includes a blend including: a high acid ionomerincluding greater than about 16 percent acid groups by weight of thehigh acid ionomer, wherein up to about 70 percent of the acid groups areneutralized by a suitable cationic source; a metallocene catalyzedpolymer including at least one grafted moiety, wherein the graftedmoiety is selected from the group consisting of maleic anhydride,fumaric anhydride, and itaconic anhydride; and a melt flow modifierincluding greater than about 16 weight percent acid groups by weight ofthe melt flow modifier.

In one embodiment, between about 30 and about 60 percent of the acidgroups are neutralized. In another embodiment, the cationic sourceincludes at least one of the group including magnesium, sodium,potassium, cesium, calcium, barium, manganese, copper, zinc, tin, andlithium.

The blend may include about 10 to about 40 pph of the metallocenecatalyzed polymer based on the total blend. In one embodiment, the blendincludes about 80 to about 64 pph of the high acid ionomer based on thetotal blend and about 3 to about 4 pph of the melt flow modifier basedon the total blend.

The present invention is also related to a golf ball including: a core;a casing layer disposed about the core, wherein the casing layerincludes a blend including: a high acid ionomer including greater thanabout 16 percent acid groups by weight of the high acid ionomer, whereinbetween about 25 percent and 70 percent of the acid groups areneutralized; and a metallocene catalyzed polymer including at least onegrafted moiety; and a cover, wherein the cover is cast from a polyureamaterial.

In this aspect of the invention, the blend may further include a meltflow modifier including greater than about 16 weight percent acid groupsby weight of the melt flow modifier. In one embodiment, the blendincludes about 16 to about 33 pph of the metallocene catalyzed polymerand about 84 to about 67 pph of the high acid ionomer based on the totalblend. In another embodiment, the blend includes about 16 to about 33pph of the metallocene catalyzed polymer and about 80 to about 64 pph ofthe high acid ionomer based on the total blend based on the total blend.In still another embodiment, the blend includes about 4 percent or lessmelt flow modifier by weight of the blend.

The high acid ionomer may include between about 17 and 25 weight percentacid groups. In one embodiment, the at least one grafted moiety isselected from the group consisting of maleic anhydride, fumaricanhydride, and itaconic anhydride. In another embodiment, between about30 and about 60 percent of the acid groups are neutralized.

The present invention is also directed to a golf ball including: a core;a casing layer disposed about the core, wherein the casing layerincludes a blend including: a high acid ionomer including greater thanabout 16 percent acid groups by weight of the high acid ionomer, whereinabout 70 percent or less of the acid groups are neutralized with a metalcation; a metallocene catalyzed polymer including at least one graftedmoiety; and a melt flow modifier including greater than about 16 weightpercent acid groups by weight of the melt flow modifier; and a cover,wherein the cover is cast from a polyurea material.

In this aspect of the invention, the cover may have a hardness of about30 to about 55 Shore D. In one embodiment, the at least one graftedmoiety is selected from the group consisting of maleic anhydride,fumaric anhydride or itaconic anhydride. The high acid ionomer may bepresent in the blend in an amount of about 84 pph to about 67 pph basedon the total blend, about 16 to about 33 pph of the metallocenecatalyzed polymer based on the total blend, and between about 2 and 4pph of the melt flow modifier based on the total blend.

The present invention is also related to a golf ball including: a core;a casing layer disposed about the core, wherein the casing layerincludes a blend including: a high acid ionomer including greater thanabout 16 percent acid groups by weight of the high acid ionomer, whereinbetween about 25 percent and about 70 percent of the acid groups areneutralized with a metal cation; a metallocene catalyzed polymerincluding at least one grafted moiety; and a melt flow modifierincluding greater than about 16 weight percent acid groups by weight ofthe melt flow modifier; and a cover having a hardness of about 30 toabout 55 Shore D and including a composition formed from a polyurethaneprepolymer and a hydroxy-terminated curing agent, wherein thepolyurethane prepolymer includes the reaction product of an isocyanateand a hydroxy-terminated component.

In this aspect of the invention, the at least one grafted moiety may beselected from the group consisting of maleic anhydride, fumaricanhydride or itaconic anhydride. In one embodiment, the high acidionomer is present in the blend in an amount of about 84 pph to about 67pph based on the total blend. In another embodiment, the blend includesabout 10 to about 40 pph of the metallocene catalyzed polymer based onthe total blend. In still another embodiment, the blend includes betweenabout 2 and 4 pph of the melt flow modifier based on the total blend.

In one embodiment, between about 30 and 60 percent of the acid groupsare neutralized in the high acid ionomer. In another embodiment, thecore includes polybutadiene. In addition, the metallocene catalyzedpolymer may include a copolymer of ethylene and butene and also maleicanhydride.

The present invention is also directed to a golf ball including: a core;a casing layer disposed about the core, wherein the casing layerincludes a blend including: a high acid ionomer including greater thanabout 16 percent acid groups by weight of the high acid ionomer, whereinbetween about 25 percent and about 70 percent of the acid groups areneutralized with a metal cation; and a metallocene catalyzed polymerincluding at least one grafted moiety; and a cover including acomposition formed from a polyurethane prepolymer and ahydroxy-terminated curing agent, wherein the polyurethane prepolymerincludes the reaction product of an isocyanate and a hydroxy-terminatedcomponent. In one embodiment, the high acid ionomer may be present inthe blend in an amount ranging from about 84 to about 67 pph based onthe total blend, the metallocene catalyzed polymer may be present in theblend in an amount ranging from about 16 to about 33 pph based on thetotal blend.

In this aspect of the invention, the blend may further include a meltflow modifier, which may be present in the blend in an amount betweenabout 2 and 4 pph based on the total blend. The melt flow modifier mayinclude greater than about 16 percent acid groups by weight of the meltflow modifier.

In one embodiment, between about 30 percent and about 60 percent of theacid groups in the high acid ionomer are neutralized. In anotherembodiment, the at least one grafted moiety includes maleic anhydride.In still another embodiment, the core includes polybutadiene.

The present invention also relates to a golf ball including: a core; acasing layer disposed about the core, wherein the casing layer includesa blend including: a high acid ionomer including between about 17 and 25percent acid groups by weight of the high acid ionomer, wherein betweenabout 30 percent and about 60 percent of the acid groups are neutralizedwith a metal cation; and a metallocene catalyzed polymer having thefollowing general formula:

wherein R₇ includes a hydrogen, a linear or branched alkyl group, anaromatic or heterocyclic group, or a combination thereof; R₈, R₉, R₁₁,and R₁₂ includes a hydrogen, a lower alkyl group including 1 to 5 carbonatoms, a carbocyclic group, an aromatic or heterocyclic group, or acombination thereof; and x, y, and z are the relative percentages ofeach co-monomer, wherein x ranges from 1 percent to 99 percent, y rangesfrom 99 percent to 1 percent, and z ranges from 0 percent to 49 percent;and a cover including a composition formed from a polyurethaneprepolymer and a hydroxy-terminated curing agent, wherein thepolyurethane prepolymer includes the reaction product of an isocyanateand a hydroxy-terminated component.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention can be ascertained fromthe following detailed description that is provided in connection withthe drawing(s) described below:

FIG. 1 is a cross-sectional view of a two-piece golf ball, wherein thecore is formed from a composition of the invention;

FIG. 2 is a cross-sectional view of a multi-component golf ball, whereinthe core is formed from a composition of the invention;

FIG. 3 is a cross-sectional view of a multi-component golf ball having alarge core, wherein at least the core is formed from a composition ofthe invention; and

FIG. 4 is a cross-sectional view of a multi-component golf ballincluding a core and a dual cover, wherein at least the core is formedfrom a composition of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The compositions of the invention provide an alternative to conventionalionomeric materials that are typically used as outer covers on largecore balls or inner covers on multilayer balls with relatively softcovers. In particular, the compositions of the invention are based on ahigh acid ionomer where the acid groups have been at least partiallyneutralized and, in some embodiments, highly neutralized, with a maleicanhydride grafted thereto. The resulting composition may be used in anytype of golf ball. In one embodiment, the golf ball includes a core anda cover and the composition of the invention is formed into a casinglayer situated between the core and the cover.

The present invention also explores the methods of making suchcompositions and other golf ball constructions that incorporate thecompositions of the invention in at least a portion thereof. In fact,the compositions of the invention can be used with a variety of golfball constructions. For example, the compositions of the invention maybe used as a cover layer in a two-piece ball with a large core, an outercover layer in a three-piece ball with a relatively thin inner coverlayer, an intermediate layer in a three-piece ball, or an inner coverlayer in a golf ball having dual cover layers. The compositioncomponents, golf ball constructions, and layer and ball properties arediscussed in greater detail below.

The Compositions of the Invention

The compositions of the invention may be formed by reactive blending asingle partially or highly neutralized high acid ionomer with a maleicanhydride grafted metallocene copolymer. The components of thecompositions of the invention are discussed below.

High Acid Ionomer

The compositions of the invention include a “high acid” ionomer. Ingeneral, ionic copolymers including up to about 16 percent acid areconsidered “low acid” ionomers. As used herein, the term “high acid”refers to ionomers that include greater than about 16 percent acidmoieties.

A high acid ionomer suitable for use with the present invention may be acopolymer of an olefin, e.g., ethylene, and at least 16 weight percentof an α,β-ethylenically unsaturated carboxylic acid, e.g., acrylic ormethacrylic acid, wherein about 10 percent to about 99 percent of thecarboxylic acid groups are neutralized with a suitable cation, e.g.,zinc, sodium, magnesium or lithium.

In one embodiment of the present invention, the high acid ionomer is“partially neutralized.” As used herein, the term “partiallyneutralized” refers to acid polymers with up to about 70 weight percentof the acid groups neutralized. As such, the term “partially neutralizedhigh acid ionomer” refers to an ionomer including greater than about 16weight percent acid groups (by weight of the ionomer) where up to about70 percent of the acid groups are neutralized with a suitable cation.For example, a partially neutralized high acid ionomer contemplated bythe present invention may have an acid neutralization level betweenabout 25 percent and about 70 percent. In one embodiment, theneutralization level is between about 30 percent and 60 percent. Inanother embodiment, the neutralization level is between about 35 percentand 55 percent.

In another embodiment of the present invention, the high acid ionomer is“highly neutralized.” The term “highly neutralized” as used hereinrefers to acid polymers with greater than about 70 percent of the acidmoieties therein neutralized. Because the high acid ionomer requiresacid groups to react with the grafted metallocene, at least 1 percent ofthe acid groups in the ionomer must not be neutralized. Accordingly, theterm “highly neutralized high acid ionomer” as used herein refers to anionomer including greater than about 16 weight percent acid groups (byweight of the ionomer) where more than about 70 percent, but less notmore 99 percent, of the acid groups in the ionomer are neutralized. Forexample, a highly neutralized high acid ionomer may have between about71 percent and 99 percent of its groups neutralized, preferably about 72percent to about 99 percent. In one embodiment, the neutralization levelfor a highly neutralized high acid ionomer for use with the presentinvention is between about 75 percent and about 98 percent, preferablyabout 80 to about 98 percent. In another embodiment, the neutralizationlevel is between about 80 percent and about 96 percent, preferably about82 percent to about 96 percent. The unneutralized acid content in thehigh acid ionomer may range from about 1 percent to about 28 percent,preferably about 2 percent to about 20 percent, and more preferablyabout 4 percent to about 18 percent.

Methods of preparing ionomers are well known, and are disclosed, forexample, in U.S. Pat. No. 3,264,272, the entire disclosure of which ishereby incorporated herein by reference. The acid copolymer can be adirect copolymer wherein the polymer is polymerized by adding allmonomers simultaneously, as disclosed, for example, in U.S. Pat. No.4,351,931, the entire disclosure of which is incorporated herein byreference. Alternatively, the acid copolymer can be a graft copolymerwherein a monomer is grafted onto an existing polymer, as disclosed, forexample, in U.S. Patent Application Publication No. 2002/0013413, theentire disclosure of which is hereby incorporated herein by reference.For example, ionomers for use with the present invention may be obtainedby providing a cross metallic bond to polymers of monoolefin with atleast one member selected from the group consisting of unsaturated mono-or di-carboxylic acids having 3 to 12 carbon atoms and esters thereof(the polymer contains 1 to 50 percent by weight of the unsaturated mono-or di-carboxylic acid and/or ester thereof). More particularly, suchacid-containing ethylene copolymer ionomer component includes E/X/Ycopolymers where E is ethylene, X is a softening comonomer such asacrylate or methacrylate present in 0 to 50 weight percent of thepolymer (preferably 0-25 wt. %, most preferably 0-20 wt. %), and Y isacrylic or methacrylic acid present in greater than about 16 weightpercent of the polymer.

In one embodiment, the high acid ionomer is a copolymer of ethylene andabout 17 weight percent to about 20 weight percent (meth)acrylic acid.In another embodiment, the high acid ionomer is a copolymer of ethyleneand between about 20 weight percent and about 25 weight percentmeth(acrylic acid).

Specific acid-containing ethylene copolymers include ethylene/acrylicacid, ethylene/methacrylic acid, ethylene/acrylic acid/n-butyl acrylate,ethylene/methacrylic acid/n-butyl acrylate, ethylene/methacrylicacid/iso-butyl acrylate, ethylene/acrylic acid/iso-butyl acrylate,ethylene/methacrylic acid/n-butyl methacrylate, ethylene/acrylicacid/methyl methacrylate, ethylene/acrylic acid/methyl acrylate,ethylene/methacrylic acid/methyl acrylate, ethylene/methacrylicacid/methyl methacrylate, and ethylene/acrylic acid/n-butylmethacrylate. Preferred acid containing ethylene copolymers includeethylene/methacrylic acid, ethylene/acrylic acid, ethylene/methacrylicacid/n-butyl acrylate, ethylene/acrylic acid/n-butyl acrylate,ethylene/methacrylic acid/methyl acrylate and ethylene/acrylicacid/methyl acrylate copolymers. The most preferred acid-containingethylene copolymers are ethylene/methacrylic acid, ethylene/acrylicacid, ethylene/(meth)acrylic acid/n-butyl acrylate,ethylene/(meth)acrylic acid/ethyl acrylate, and ethylene/(meth)acrylicacid/methyl acrylate copolymers.

Suitable cation sources include metal ions and compounds of alkalimetals, alkaline earth metals, and transition metals; metal ions andcompounds of rare earth elements; silicone, silane, and silicatederivatives and complex ligands; and combinations thereof. Preferredcation sources are metal ions and compounds of magnesium, sodium,potassium, cesium, calcium, barium, manganese, copper, zinc, tin,lithium, and rare earth metals.

In the case of a highly neutralized high acid ionomer for use with thepresent invention, the acid copolymer may be at least partiallyneutralized prior to contacting the acid copolymer with a cation sourceto form a highly neutralized high acid ionomer.

The partially and highly neutralized high acid ionomers for use with thepresent invention have the following general structure:

where:

-   -   R₁ may be hydrogen, linear or branched alkyl such as methyl,        ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl,        carbocyclic, aromatic or heterocyclic;    -   R₂ may be hydrogen, lower alkyl including C₁-C₅, carbocyclic,        aromatic or heterocyclic;    -   R₃ may be hydrogen, lower alkyl including C₁-C₅, carbocyclic,        aromatic or heterocyclic;    -   R₄ may be hydrogen, lower alkyl including C₁-C₅, carbocyclic,        aromatic or heterocyclic;    -   R₅ may be hydrogen, lower alkyl including C₁-C₅, carbocyclic,        aromatic or heterocyclic;    -   R₆ may be hydrogen, lower alkyl including C₁-C₅, carbocyclic,        aromatic or heterocyclic; and    -   x, y, and z are the relative percentages of each co-monomer        where the number x can range from 1 percent to 99 percent or        more preferably from 10 percent to 70 percent and most        preferred, from about 10 percent to about 50 percent. The number        y can be from 99 percent to 1 percent, preferably, from 90        percent to 30 percent, or most preferably, 90 percent to 50        percent. The number z can range from 0 percent to 49 percent.

In one embodiment, the high acid ionomer is a copolymer of ethylene andabout 17 weight percent to about 20 weight percent methacrylic acidwherein about 35 percent to about 99 percent of the carboxylic acidgroups are neutralized by sodium. Examples of commercially availablehigh acid ionomers include SURLYN® 8140, which is an ethylene-basedionomer believed to include about 17 weight percent to about 20 weightpercent methacrylic acid with acid groups neutralized with sodium.

The hardness of the high acid ionomer will vary depending on the acidcontent and the neutralization level. In one embodiment, the high acidionomer has a hardness ranging from at least about 50 Shore D,preferably at least about 54 Shore D, and more preferably about 58 ShoreD or greater. In another embodiment, the material hardness of theionomer is from about 60 Shore D to about 70 Shore D.

The flexural modulus of the high acid ionomer preferably ranges fromabout 50,000 psi to about 80,000 psi. In one embodiment, the high acidionomer has a flexural modulus of about 55,000 psi to about 75,000 psi.In another embodiment, the high acid ionomer has a flexural modulus ofabout 60,000 psi to about 70,000 psi.

Grafted Metallocene Copolymer

The partially and highly neutralized high acid ionomers described aboveare preferably reactive blended with at least one grafted metallocenecatalyzed polymer. Suitable grafted metallocene catalyzed polymers foruse with the present invention may include an olefinic polymer graftedwith at least one functional group such as epoxy, anhydride, amine,oxazoline, sulfonic acid, carboxylic acid and their salts. In oneembodiment of the present invention, the grafted metallocene catalyzedpolymer includes an anhydride group.

As used herein, the term “olefinic polymer” means a polymer, copolymer,terpolymer or terpolymer comprised of at least one olefin with attachedlinear or branched alkyl groups having from about 1 to about 18 carbonatoms. The term “olefinic polymer” is specifically meant to include thefollowing materials: a polymer including an α-olefin containing from 2to 10 carbon atoms; polymers formed with the use of metallocenecatalysts and including monomers selected from the group consisting ofbutene, hexene, and octene; polymers formed with the use of metallocenecatalysts and selected from the group consisting of a copolymer ofethylene and butene, a copolymer of ethylene and hexene and a copolymerof ethylene and octene; a terpolymer formed with the use of metallocenecatalysts and consisting essentially of a polymer of ethylene,propylene, and a diene monomer; copoly(ethylene-vinyl alcohol); acopolymer consisting essentially of an-olefin monomer containing from 2to 10 carbon atoms and an alkyl acrylate or an alkyl alkylacrylatemonomer, wherein each alkyl group ranges, independently, from methyl todecyl inclusive and may be linear or branched; a copolymer consistingessentially of an-olefin monomer containing from 2 to 10 carbon atomsand a glycidyl acrylate or a glycidyl alkylacrylate monomer, wherein thealkyl group ranges from methyl to decyl inclusive and may be linear orbranched; a terpolymer consisting essentially of an-olefin monomercontaining from 2 to 10 carbon atoms, an alkyl acrylate or an alkylalkylacrylate monomer, and a glycidyl acrylate or a glycidylalkylacrylate monomer, wherein each alkyl group ranges, independently,from methyl to decyl inclusive and may be linear or branched; acopolymer consisting essentially of an-olefin monomer containing from 2to 10 carbon atoms and a vinyloxazoline or 1-alkyl vinyloxazolinemonomer, wherein the alkyl group ranges from methyl to decyl inclusiveand may be linear or branched; a terpolymer consisting essentially ofan-olefin monomer containing from 2 to 10 carbon atoms, an alkylacrylate or an alkyl alkylacrylate monomer, and a vinyloxazoline or1-alkyl vinyloxazoline monomer, wherein each alkyl group ranges,independently, from methyl to decyl inclusive and may be linear orbranched; a copolymer consisting essentially of an-olefin monomercontaining from 2 to 10 carbon atoms and carbon monoxide; a terpolymerconsisting essentially of a first-olefin monomer containing from 2 to 10carbon atoms, a second-olefin monomer containing from 2 to 10 carbonatoms, and carbon monoxide; a copolymer consisting essentially ofan-olefin monomer containing from 2 to 10 carbon atoms and sulfurdioxide; a terpolymer consisting essentially of a first-olefin monomercontaining from 2 to 10 carbon atoms, a second-olefin monomer containingfrom 2 to 10 carbon atoms, and sulfur dioxide; a copolymer consistingessentially of an-olefin monomer containing from 2 to 10 carbon atomsand maleic anhydride; a terpolymer consisting essentially of an-olefinmonomer containing from 2 to 10 carbon atoms, maleic anhydride, andcarbon monoxide; a terpolymer consisting essentially of an-olefinmonomer containing from 2 to 10 carbon atoms, maleic anhydride, andsulfur dioxide; and a terpolymer consisting essentially of an-olefinmonomer containing from 2 to 10 carbon atoms, maleic anhydride, and analkyl acrylate or an alkyl alkylacrylate monomer, wherein each alkylgroup ranges, independently, from methyl to decyl inclusive and may belinear or branched. Furthermore, the term “olefinic polymers” alsoencompasses mixtures of at least two olefinic polymers.

As used herein, the term “metallocene catalyst” refers to a single-sitecatalyst wherein the ancillary ligands include substituted orunsubstituted cyclopentadienyl groups. Accordingly, the term“metallocene catalyzed polymer” refers to any polymer, copolymer, orterpolymer, and, in particular, any polyolefin, polymerized using ametallocene catalyst. The term “metallocene catalyzed polymer blend”refers to any blend of a metallocene catalyzed polymer and any othertype of polymer, preferably an ionomer.

As used herein, the phrase “linear or branched alkyl groups of up toabout 18 carbon atoms” means any substituted or unsubstituted acycliccarbon-containing compound, including alkanes, alkenes and alkynes. Asused herein, the phrase “alkyl group ranges from methyl to decylinclusive and may be linear or branched” means any substituted orunsubstituted acyclic carbon-containing compounds, including alkanes,alkenes and alkynes.

Examples of alkyl groups include lower alkyl, for example, methyl,ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl or tert-butyl; upperalkyl, for example, octyl, nonyl, decyl, and the like; and loweralkylene, for example, ethylene, propylene, butylene, butyldiene,pentene, hexene, heptene, octene, norbomene, nonene, decene and thelike. The ordinary skilled artisan is familiar with numerous linear andbranched alkyl groups, which are within the scope of the presentinvention.

Additionally, such alkyl groups may also contain various substituents inwhich one or more hydrogen atoms has been “grafted” or replaced by afunctional group. Functional groups include but are not limited tohydroxyl, amino, epoxy, carboxyl, sulfonic amide, ester, ether,phosphates, thiol, nitro, silane and halogen (fluorine, chlorine,bromine and iodine), to mention but a few.

Grafted metallocene catalyzed polymers for use with the invention mayalso be obtained by subjecting a commercially available non-graftedmetallocene catalyzed polymer to a post-polymerization reactioninvolving a monomer and an organic peroxide to provide a graftedmetallocene catalyzed polymer with the desired pendant group or groups.

In one embodiment of the present invention, the metallocene catalyzedpolymer has the following general structure:

where:

-   -   R₇ may be hydrogen, linear or branched alkyl such as methyl,        ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl,        carbocyclic, aromatic or heterocyclic;    -   R₈ may be hydrogen, lower alkyl including C₁-C₅, carbocyclic,        aromatic or heterocyclic;    -   R₉ may be hydrogen, lower alkyl including C₁-C₅, carbocyclic,        aromatic or heterocyclic;    -   R₁₀ may be selected from the group consisting of H,        C_(n)H_(2n+1), where n is from 1 to 18, and phenyl, in which        from 0 to 5H within R₁₀ can be replaced by substituents selected        from the group consisting of COOH, SO₃H, NH₂, F, Cl, Br, I, OH,        SH, silicone, lower alkyl esters and lower alkyl ethers;    -   R₁₁ may be hydrogen, lower alkyl including C₁-C₅, carbocyclic,        aromatic or heterocyclic;    -   R₁₂ may be hydrogen, lower alkyl including C₁-C₅, carbocyclic,        aromatic or heterocyclic; and    -   x, y, and z are the relative percentages of each co-monomer        where the number x can range from 1 percent to 99 percent or        more preferably from 10 percent to 70 percent and most        preferred, from about 10 percent to about 50 percent. The number        y can be from 99 percent to 1 percent, preferably, from 90        percent to 30 percent, or most preferably, 90 percent to 50        percent. The number z can range from 0 percent to 49 percent.

In one embodiment, R₉ and R₁₀ can be combined to form a bicyclic ring.For example, the metallocene catalyzed polymer may have the followinggeneral formula:

where R₇, R₈, R₁₁, R₁₂, x, y and z may be as defined above.

In another embodiment, R₁₀ may be functional group selected fromfumaric, itaconic, or maleic anhydride. For example, with maleicanhydride having the following formula:

the resulting grafted metallocene catalyzed polymer will have thefollowing general formula:

where R₇, R₈, R₁₁, R₁₂, x, y and z may be as defined above.

In one embodiment, the grafted metallocene catalyzed copolymer is acopolymer of ethylene-propylene, ethylene-butene, ethylene-hexene,ethylene-octene with a grafting moiety of maleic, fumaric, or itaconicanhydride.

As used herein, substituted and unsubstituted carbocyclic means cycliccarbon-containing compounds, including, but not limited to cyclopentyl,cyclohexyl, cycloheptyl, adamantyl, and the like. Such cyclic groups mayalso contain various substituents in which one or more hydrogen atomshas been replaced by a functional group. Such functional groups includethose described above, and lower alkyl groups having from 1-28 carbonatoms. The cyclic groups of the invention may further comprise aheteroatom.

Melt Flow Modifier

The compositions of the invention may include a melt flow modifier. Inone embodiment, the melt flow modifier is an ethylene-(meth)acrylic acidcopolymer with a high acid content. For example, the melt flow modifiermay be an ethylene-acrylic acid copolymer with about 17 percent to about30 percent acid groups by weight of the copolymer. In anotherembodiment, the melt flow modifier is an ethylene-acrylic acid copolymerwith about 17 percent to about 25 percent acid groups by weight of thecopolymer.

The melt flow modifier may be included in the composition in an amountranging from about 1 percent to about 4 percent by weight of theresultant polymer. In one embodiment, the melt flow modifier is includedin the composition in an amount of about 2 percent to about 4 percent byweight of the resultant polymer. In another embodiment, the melt flowmodifier is included in the composition in an amount of about 3 percentto about 4 percent by weight of the resultant polymer.

Methods of Forming the Compositions of the Invention

When the partially or highly neutralized high acid ionomer is blendedwith a grafted metallocene catalyzed copolymer, a bond is formed betweenthe acid group and the maleic anhydride to form an open-ended anhydrideof the following structure:

where R₁-R₉, R₁₁-R₁₂, and x, y, and z may be as defined previously.

In one embodiment, the composition includes about 1 pph to about 100 pphof at least one grafted metallocene catalyzed polymer and about 99 pphto 0 pph of at least one ionomer. In another embodiment, the graftedmetallocene catalyzed polymer is present in an amount of about 10 toabout 45 pph based on the total blend, preferably about 10 pph to about40 pph based on the total blend. In yet another embodiment, the graftedmetallocene catalyzed polymer is present in an amount of about 16 toabout 33 pph based on the total blend, preferably about 16 to about 24pph based on the total blend. For example, the grafted metallocenecatalyzed polymer may be present in an amount of about 16 pph, 19 pph,or 24 pph based on the total blend. In still another embodiment, thegrafted metallocene catalyzed polymer is present in an amount of about14 pph to about 26 pph based on the total blend.

The high acid ionomer is preferably present in an amount of about 90 toabout 55 pph based on the total blend, preferably about 90 pph to about50 pph based on the total blend. In one embodiment, the high acidionomer is present in an amount of about 84 to about 64 pph based on thetotal blend, preferably about 80 pph to about 67 pph. In anotherembodiment, the high acid ionomer is present in an amount of about 86pph to about 74 pph based on the total blend.

As discussed above, the compositions of the invention preferably includea melt flow modifier. When present, the melt flow modifier is includedin an amount of about 4 weight percent or less of the polymer. In oneembodiment, the melt flow modifier is included in an amount of about 3pph to about 4 pph based on the total blend. In another embodiment, themelt flow modifier is included in an amount of about 3 pph to about 4pph based on the total blend.

The melt flow index (MFI) of the compositions of the invention may be atleast about 2.0, preferably about 1.5 g/10 min using a 2.16 kg load. Inone embodiment, the MFI of the compositions of the invention ranges fromabout 2.0 to about 4.5 g/10 min.

The compositions of the present invention may also include additionalcomponents including, but not limited to fillers, additives, and/or meltflow modifiers. For example, suitable melt flow modifiers include, butare not limited to, high molecular weight organic acids and saltsthereof, polyamides, polyesters, polyacrylates, polyurethanes,polyethers, polyureas, polyhydric alcohols, and combinations thereof.Suitable organic acids are aliphatic organic acids, aromatic organicacids, saturated mono-functional organic acids, unsaturatedmonofunctional organic acids, multi-unsaturated mono-functional organicacids, and dimerized derivatives thereof. Particular examples ofsuitable organic acids include, but are not limited to, caproic acid,caprylic acid, capric acid, lauric acid, stearic acid, behenic acid,erucic acid, oleic acid, linoleic acid, myristic acid, benzoic acid,palmitic acid, phenylacetic acid, naphthalenoic acid, dimerizedderivatives thereof.

The compositions of the invention may also be foamed. Suitable foamingagents include, but are not limited to, organic blowing agents, such asazobisformamide; azobisisobutyronitrile; diazoaminobenzene;N,N-dimethyl-N,N-dinitroso terephthalamide;N,N-dinitrosopentamethylene-tetramine; benzenesulfonyl-hydrazide;benzene-1,3-disulfonyl hydrazide; diphenylsulfon-3-3, disulfonylhydrazide; 4,4′-oxybis benzene sulfonyl hydrazide; p-toluene sulfonylsemicarbizide; barium azodicarboxylate; butylamine nitrile; nitroureas;trihydrazino triazine; phenyl-methyl-uranthan; p-sulfonhydrazide;peroxides; and inorganic blowing agents such as ammonium bicarbonate andsodium bicarbonate. A gas, such as air, nitrogen, carbon dioxide, etc.,can also be injected into the composition during the injection moldingprocess. In addition, a composition of the present invention may beformed by blending microspheres with the composition either during orbefore the molding process. Polymeric, ceramic, metal, and glassmicrospheres are useful in the invention, and may be solid or hollow andfilled or unfilled. In particular, microspheres up to about 1000micrometers in diameter are useful. Furthermore, the use of liquidnitrogen for foaming, as disclosed in U.S. Pat. No. 6,386,992, which isincorporated by reference herein, may produce highly uniform foamedcompositions for use in the present invention.

Fillers may also be added to the compositions of the invention to affectrheological and mixing properties, the specific gravity (i.e.,density-modifying fillers), the modulus, the tear strength,reinforcement, and the like. The fillers are generally inorganic, andsuitable fillers include numerous metals, metal oxides and salts, suchas zinc oxide and tin oxide, as well as barium sulfate, zinc sulfate,calcium carbonate, zinc carbonate, barium carbonate, clay, tungsten,tungsten carbide, an array of silicas, regrind (recycled core materialtypically ground to about 30 mesh particle), high-Mooney-viscosityrubber regrind, and mixtures thereof.

For example, the compositions of the invention can be reinforced byblending with a wide range of density-adjusting fillers, e.g., ceramics,glass spheres (solid or hollow, and filled or unfilled), and fibers,inorganic particles, and metal particles, such as metal flakes, metallicpowders, oxides, and derivatives thereof, as is known to those withskill in the art. The selection of such filler(s) is dependent upon thetype of golf ball desired, i.e., one-piece, two-piece, multi-component,or wound, as will be more fully detailed below. Generally, the fillerwill be inorganic, having a density of greater than 4 g/cc, and will bepresent in amounts between about 5 and about 65 weight percent based onthe total weight of the polymer components included in the layer(s) inquestion. Examples of useful fillers include zinc oxide, barium sulfate,calcium oxide, calcium carbonate, and silica, as well as other knowncorresponding salts and oxides thereof.

The compositions of the present invention may also be blended with otherpolymers into a single composite. For example, the compositions of theinvention may be present in a blend with ionomeric copolymers orterpolymers, ionomeric precursors, thermoplastics, polyamides,polycarbonates, polyesters, polyurethanes, polyureas, thermoplasticelastomers, polybutadiene rubber, balata, grafted and non-graftedmetallocene-catalyzed polymers, single-site polymers, high-crystallineacid polymers, cationic polymers, cationic and anionic urethane ionomersand urethane epoxies, polyurethane ionomers, polyurea ionomers, epoxyresins, polyethylenes, polyacrylin, siloxanes, and mixtures thereof. Oneof ordinary skill in the art would be well aware of methods to blendthese polymeric materials with the composition of the invention to forma composition for use in golf ball layers.

Golf Ball Construction

As discussed briefly above, the compositions of the present inventionmay be used with any type of ball construction including, but notlimited to, one-piece, two-piece, three-piece, and four-piece designs, adouble cover, an intermediate layer(s), and/or a multi-layer coverdepending on the type of performance desired of the ball.

As used herein, the term “multilayer” means at least two layers. As usedherein, the term “center” is used to reference the innermost componentof the core. In some embodiments, however, the term “center” may be usedinterchangeably with the term “core”.

When the golf ball of the present invention includes an intermediatelayer, which may also include more than one layer, this layer may beincorporated with a single or multilayer cover, or with both a singlelayer cover and core. The intermediate layer may be also be referred toas an inner cover layer or outer core layer, or any other layer(s)disposed between the inner core and the outer cover of a golf ball.

Referring to FIG. 1, a golf ball 2 of the present invention may includea center 4 and a cover 6 surrounding the center 4. While dimensions andmaterials are discussed in more detail below, a golf ball of theinvention can include a large core, e.g., from about 1.55 inches toabout 1.60 inches, and a relatively soft, thin cover formed from thecomposition of the invention.

Referring to FIG. 2, a golf ball 8 of the present invention may includea center 10, a cover 14, and at least one intermediate layer 12 disposedbetween the cover and the center. For example, in one embodiment, thecompositions of the invention may be used to form the intermediate layer12, which may be disposed between a polybutadiene core 10 and arelatively thin, i.e., about 0.02 inches to about 0.045 inches,polyurethane or polyurea cover 14. Each of the cover and center layersin FIG. 1 or 2 may include more than one layer, i.e., the golf ball canbe a conventional three-piece wound ball, a two-piece ball, a ballhaving a multi-layer core and an intermediate layer or layers, etc.Also, FIG. 3 shows a golf ball 16 of the present invention including alarge core 18, a cover 22, and an inner cover layer 20. In oneembodiment, the core 18 includes a center and an outer core layer. Inone embodiment, the compositions of the invention may be used to formthe inner cover layer 20, which may be disposed between a polybutadienecore 18 and a relatively thin, i.e., about 0.02 inches to about 0.045inches, polyurethane or polyurea cover 22.

In another embodiment, as shown in FIG. 4, a golf ball 24 of the presentinvention may include a large core having a center 26 and anintermediate layer 28 disposed underneath a dual cover having an innercover layer 30 and an outer cover layer 32. In one embodiment, the innercover layer 30 is formed from the composition of the invention. Further,any of the figures detailed herein may include embodiments wherein anoptional wound layer is disposed between the center and the core of thegolf ball.

Other non-limiting examples of suitable types of ball constructions thatmay be used with the present invention include those described in U.S.Pat. Nos. 6,056,842, 5,688,191, 5,713,801, 5,803,831, 5,885,172,5,919,100, 5,965,669, 5,981,654, 5,981,658, and 6,149,535, as well as inPublication Nos. US2001/0009310 A1, US2002/0025862, and US2002/0028885.The entire disclosures of these patents and published patentapplications are incorporated by reference herein.

Golf Ball Intermediate Layer(s)

When the golf ball of the present invention includes an intermediatelayer, such as an inner cover layer or outer core layer, i.e., anylayer(s) disposed between the inner core and the outer cover of a golfball, this layer can include any materials known to those of ordinaryskill in the art including thermoplastic and thermosetting materials.

In one embodiment, the intermediate layer is formed, at least in part,from the composition of the invention. For example, an intermediatelayer or inner cover layer having a thickness of about 0.015 inches toabout 0.06 inches may be disposed about a core to form an inner ball. Inthis aspect of the invention, the core, which has a diameter rangingfrom about 1.5 inches to about 1.59 inches, may also be formed from acomposition of the invention or, in the alternative, from a conventionalrubber composition. The inner ball may then be covered by a castablethermoset or injection moldable thermoplastic material or any of theother cover materials discussed below. In this aspect of the invention,the cover may have a thickness of about 0.02 inches to about 0.045inches, preferably about 0.025 inches to about 0.04 inches. The corecompression is about 30 to about 110 atti, preferably about 50 to about100 atti, and the overall ball compression preferably ranges from about50 to about 100 atti.

In another embodiment, the intermediate layer is covered by an innercover layer, either of which may independently be formed from thecompositions of the invention. For example, a ball of the invention mayinclude a center having a diameter of about 0.5 inches to about 1.30inches and a compression of about 30 to about 110 atti, preferably about50 to about 100 atti. The center may be formed from a composition of theinvention or any of the other core materials previously discussed. Thecore may be covered by an outer core layer to form a core, which alsomay be formed form the compositions of the invention, any of the corematerials discussed above, or castable thermoset materials or injectionmoldable thermoplastic materials. The outer core layer may have athickness of about 0.125 inches to about 0.500 inches. The core may thenbe covered with a casing layer having a thickness of about 0.015 inchesto about 0.06 inches formed from a composition of the invention, acastable thermoset material or an injection moldable thermoplasticmaterial. The outer cover layer, which preferably has a thickness ofabout 0.02 inches to about 0.045 inches, may be formed from a castablethermoset material or an injection moldable thermoplastic material orother suitable cover materials discussed below and known in the art.

When not formed from the compositions of the invention, the intermediatelayer(s) may also be formed, at least in part, from one or morehomopolymeric or copolymeric materials, such as ionomers, primarily orfully non-ionomeric thermoplastic materials, vinyl resins, polyolefins,polyurethanes, polyureas, such as those disclosed in U.S. Pat. No.5,484,870, polyamides, acrylic resins and blends thereof, olefinicthermoplastic rubbers, block copolymers of styrene and butadiene,isoprene or ethylene-butylene rubber, copoly(ether-amide), such asPEBAX, sold by Arkema, Inc. of Philadelphia, Pa., polyphenylene oxideresins or blends thereof, and thermoplastic polyesters.

For example, the intermediate layer may be formed of low acid ionomers,such as those described in U.S. Pat. Nos. 6,506,130 and 6,503,156, highacid ionomers, highly neutralized polymers, such as those disclosed inU.S. Patent Publication Nos. 2001/0018375 and 2001/0019971, or mixturesthereof. The intermediate layer may also be formed from the compositionsas disclosed in U.S. Pat. No. 5,688,191. The entire disclosures of thesepatents and publications are incorporated herein by express referencethereto.

In one embodiment, the intermediate layer may be a moisture barrierlayer as disclosed in U.S. Pat. No. 6,632,147. Thus, a golf ball of theinvention may include an intermediate layer that has a moisture vaportransmission rate lower than that of the cover and, additionally, aprimary ingredient of the intermediate layer is made from a materialincluding polybutadiene, natural rubber, butyl-based rubber, acrylics,trans-polyisoprene, neoprene, chlorinated polyethylene, balata,multi-layer thermoplastic films, blends of ionomers, polyvinyl alcoholcopolymer and polyamides, and dispersions of acid salts ofpolyetheramines. In another embodiment, golf balls of the inventioninclude an intermediate layer or inner cover layer formed from thecompositions of the invention and an additional moisture barrier layer.

The intermediate layer may also include a wound layer formed from atensioned thread material. The thread may be single-ply or may includetwo or more plies. Suitable thread materials include, but are notlimited to, fiber, glass, carbon, polyether urea, polyether blockcopolymers, polyester urea, polyester block copolymers, syndiotactic- orisotactic-poly(propylene), polyethylene, polyamide, poly(oxymethylene),polyketone, poly(ethylene terephthalate), poly(p-phenyleneterephthalamide), poly(acrylonitrile), diaminodicyclohexylmethane,dodecanedicarboxylic acid, natural rubber, polyisoprene rubber,styrene-butadiene copolymers, styrene-propylene-diene copolymers,another synthetic rubber, or block, graft, random, alternating, brush,multi-arm star, branched, or dendritic copolymers, or mixtures thereof.Those of ordinary skill in the art are aware of the process forproducing thread materials for use with the present invention.

Golf Ball Cover Layer(s)

The cover provides the interface between the ball and a club. Propertiesthat are desirable for the cover are good moldability, high abrasionresistance, high impact resistance, high tear strength, high resilience,and good mold release, among others. The cover layer may be formed, atleast in part, from a composition of the invention. For example, thepresent invention contemplates a golf ball having a large core ofpolybutadiene and a thin cover formed from the composition of theinvention.

When not formed from the composition of the present invention, the coverlayer may be formed from thermoplastic or thermoset polyurethane- orpolyurea-based polymers. In one embodiment of the invention, thecompositions of the invention are used to form a casing layer over acore to form an inner ball, which is then covered with a polyurea orpolyurethane material. Suitable polyurea and polyurethane materials foruse in this aspect of the invention are discussed below.

Both polyurethane and polyureas are typically formed from anisocyanate-containing component and an isocyanate-reactive component.For example, polyureas may be prepared from at least one isocyanate andat least one amine-terminated compound, which results in a polymer withurea linkages. In contrast, polyurethanes may be prepared from at leastone isocyanate and at least one hydroxy-terminated compound, whichresults in a polymer with urethane linkages.

Either type of material may be formed using the one-shot method or theprepolymer method. The one-shot technique reacts theisocyanate-containing component, the isocyanate-reactive component, anda curative in one step, whereas the prepolymer technique requires afirst reaction between the isocyanate-reactive component(s) and anisocyanate to produce a prepolymer and a subsequent reaction between theprepolymer and a curative. Either method may be employed to produce thecompositions of the invention, however, the prepolymer technique ispreferred because it provides better control of chemical reaction and,consequently, results in more uniform properties for the elastomers.

Any isocyanate available to one of ordinary skill in the art is suitablefor use as the isocyanate-containing component. Thus, isocyanates foruse with the present invention may include aliphatic, cycloaliphatic,aromatic aliphatic, any derivatives thereof, and combinations of thesecompounds having two or more isocyanate (NCO) groups per molecule. Asused herein, aromatic aliphatic compounds should be understood as thosecontaining an aromatic ring, wherein the isocyanate group is notdirectly bonded to the ring. One example of an aromatic aliphaticcompound is a tetramethylene diisocyanate (TMXDI). The isocyanates maybe organic polyisocyanate-terminated prepolymers, low free isocyanateprepolymer, and mixtures thereof. The isocyanate-containing reactablecomponent may also include any isocyanate-functional monomer, dimer,trimer, or polymeric adduct thereof, prepolymer, quasi-prepolymer, ormixtures thereof. Isocyanate-functional compounds may includemonoisocyanates or polyisocyanates that include any isocyanatefunctionality of two or more.

Suitable isocyanate-containing components include diisocyanates havingthe generic structure: O═C═N—R—N═C═O, where R is preferably a cyclic orlinear or branched hydrocarbon moiety containing from about 1 to about20 carbon atoms. When multiple cyclic groups are present, linear and/orbranched hydrocarbons containing from about 1 to about 10 carbon atomscan be present as spacers between the cyclic groups. In some cases, thecyclic group(s) may be substituted at the 2-, 3-, and/or 4-positions, orat the ortho-, meta-, and/or para-positions, respectively. Substitutedgroups may include, but are not limited to, halogens, primary,secondary, or tertiary hydrocarbon groups, or a mixture thereof.

Examples of aliphatic isocyanates that can be used with the presentinvention include, but are not limited to, substituted and isomericmixtures including ethylene diisocyanate; propylene-1,2-diisocyanate;tetramethylene-1,2-diisocyanate; tetramethylene-1,3-diisocyanate;tetramethylene-1,4-diisocyanate; 1,6-hexamethylene diisocyanate (HDI);octamethylene diusocyanate; decamethylene diisocyanate;2,2,4-trimethylhexamethylene diisocyanate; 2,4,4-trimethylhexamethylenediisocyanate; dodecane-1,12-diisocyanate; dicyclohexylmethanediisocyanate; cyclobutane-1,3-diisocyanate;cyclohexane-1,2-diisocyanate; cyclohexane-1,3-diisocyanate;cyclohexane-1,4-diisocyanate; methylcyclohexylene diisocyanate (HTDI);2,4-methylcyclohexane diisocyanate; 2,6-methylcyclohexane diisocyanate;4,4′-dicyclohexyl diisocyanate; 2,4′-dicyclohexyl diisocyanate;1,3,5-cyclohexane triisocyanate; isocyanatomethylcyclohexane isocyanate;1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane;isocyanatoethylcyclohexane isocyanate; bis(isocyanatomethyl)-cyclohexanediisocyanate; 4,4′-bis(isocyanatomethyl)dicyclohexane;2,4′-bis(isocyanatomethyl)dicyclohexane; isophorone diisocyanate (IPDI);triisocyanate of HDI; triisocyanate of 2,2,4-trimethyl-1,6-hexanediisocyanate (TMDI); 4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI);dimerized uretdione of any aliphatic polyisocyanate, such as uretdioneof hexamethylene diisocyanate; modified polyisocyanate derived from theabove isocyanates and polyisocyanates; and mixtures thereof.

Moreover, biurets of isocyanates and isocyanurate trimers of isocyanatesare contemplated for use in the coating compositions of the invention.The general formula for each is as follows: where R and R₁ may be anyorganic radical having a valence x. In one embodiment, R is a straightor branched hydrocarbon moiety, acyclic group, cyclic group,heterocyclic group, aromatic group, phenyl group, or a mixture thereof.In another embodiment, R is unsubstituted or substituted. For example,in some cases, the cyclic or aromatic group(s) may be substituted at the2-, 3-, and/or 4-positions, or at the ortho-, meta-, and/orpara-positions, respectively. Substituted groups may include, but arenot limited to, halogens, primary, secondary, or tertiary hydrocarbongroups, or a mixture thereof.

While aliphatic isocyanates are discussed primarily herein, aromaticisocyanates are also contemplated for use with the present invention.

Any amine-terminated compound available to one of ordinary skill in theart is suitable for use as the isocyanate-reactive component to form apolyurea using the one-shot method or a polyurea prepolymer that isfurther reacted with a curative. Again, while aromatic amine-terminatedcompounds are contemplated for the present invention, aliphaticamine-terminated compounds are preferred due to improved light stabilityof the coating composition.

The amine-terminated compounds may be in the form of a primary amine(NH₂), a secondary amine (NHR), or mixtures thereof. For instance,amine-terminated hydrocarbons, amine-terminated polyethers,amine-terminated polyesters, amine-terminated polycarbonates,amine-terminated polycaprolactones, amine-terminated polyamides, andmixtures thereof are contemplated for use with the present invention.Examples of suitable amine-terminated compounds and their genericstructures are discussed in U.S. Pat. No. 6,958,379, the entiredisclosure of which is incorporated by reference herein.

Another example of an amine-terminated compound suitable for use withthe present invention is an aspartic ester, which is a secondary aminederived from a primary polyamine and a dialkyl maleic or fumaric acidester. Suitable methods for forming aspartic esters are disclosed inU.S. Pat. No. 5,243,012, which is incorporated by reference herein.Suitable primary polyamines include, but are not limited to, ethylenediamine, 1,2-diaminopropane, 1,4-diaminobutane, 1,3-diaminopentane,1,6-diaminohexane, 2,5-diamino-2,5-dimethlhexane, 2,2,4- and/or2,4,4-trimethyl-1,6-diaminohexane, 1,11-diaminoundecane,1,12-diaminododecane, 1,3- and/or 1,4-cyclohexane diamine,1-amino-3,3,5-trimethyl-5-aminomethyl-cyclohexane, 2,4- and/or2,6-hexahydrotoluylene diamine, 2,4′ and/or 4,4′-diaminodicyclohexylmethane and 3,3′-dialkyl-4,4′-diamino-dicyclohexyl methanes such as3,3′-dimethyl-4,4-diamino-dicyclohexyl methane and3,3′-diethyl-4,4′-diaminodicyclohexyl methane; aromatic polyamines suchas 2,4- and/or 2,6-diaminotoluene and 2,6-diaminotoluene and 2,4′ and/or4,4′-diaminodiphenyl methane; and polyoxyalkylene polyamines (alsoreferred to herein as amine terminated polyethers), especially diamines,as are described herein below. Mixtures of polyamines may also beemployed in preparing the aspartic esters used in the practice of thisinvention. Representative examples of useful maleic acid esters includedimethyl maleate, diethyl maleate, dibutyl maleate, dioctyl maleate, andmixtures thereof.

The aspartic ester derived polyureas have a number of advantageousproperties, such as smooth, glossy film surface, excellent elongation(high) at a high elastomer strength, excellent ultraviolet colorstability, good low temperature property retention and flexibility,slower reactivity for ease of processing and substrate wet-out (improvedadhesion). Because polyurea compositions are known to have very rapidreactions, the use of an aspartic ester is beneficial because it allowsa skilled artisan to slow down the polymerization reaction if desired.

Other amine-terminated compounds that may be useful in forming thepolyurea coatings of the present invention include, but are not limitedto, poly(acrylonitrile-co-butadiene);poly(1,4-butanediol)bis(4-aminobenzoate) in liquid or waxy solid form;linear and branched polyethylenimine; low and high molecular weightpolyethylenimine having an average molecular weight of about 500 toabout 30,000; poly(propylene glycol)bis(2-aminopropyl ether) having anaverage molecular weight of about 200 to about 5,000;polytetrahydrofuran bis(3-aminopropyl) terminated having an averagemolecular weight of about 200 to about 2000; and mixtures thereof, allof which are available from Aldrich of Milwaukee, Wis.

The molecular weight of the amine-terminated compound for use in theinvention may range from about 100 to about 10,000. As used herein, theterm “about” is used in connection with one or more numbers or numericalranges, should be understood to refer to all such numbers, including allnumbers in a range. In one embodiment, the amine-terminated compound isabout 500 or greater, preferably about 1000 or greater, and even morepreferably about 2000 or greater. In another embodiment, theamine-terminated compound molecular weight is about 8000 or less,preferably about 4,000 or less, and more preferably about 3,000 or less.For example, in one embodiment, the molecular weight of theamine-terminated compound is about 1000 to about 4000. In some cases, ahigher molecular weight amine-terminated compound is preferred. Forexample, a suitable amine-terminated compound for use with the presentinvention is an amine terminated polyether, including a primary orsecondary amine terminated polyether of greater than 1,500 averagemolecular weight, having a functionally of from about 2 to about 6,preferably from about 2 to about 3, and amine equivalent weight of fromabout 750 to about 4,000. Such amine-terminated polyethers are availableunder the tradename JEFFAMINE®, which are manufactured by HuntsmanCorporation.

In addition, by using amine-terminated moieties based on a hydrophobicsegment, the polyurea coating compositions of the invention may be morewater resistant than those polyurea coating compositions formed with anamine-terminated hydrophilic segment. Thus, in one embodiment, theamine-terminated compound includes hydrophobic backbone, e.g., anunsaturated or saturated hydrocarbon-based amine-terminated compound,preferably saturated. One example of an amine-terminated hydrocarbon isan amine-terminated polybutadiene.

The amine-terminated compound may also be blended with additionalpolyols to formulate copolymers that are reacted with excess isocyanateto form a polyurea prepolymer. Once a polyol is used, however, theexcess isocyanate in the polyurea prepolymer reacts with the hydroxylgroups in the polyol and forms urethane linkages, which results in acoating composition that is no longer pure polyurea, but instead ahybrid polyurea/urethane composition. Such a composition is distinctfrom a polyurea composition including only isocyanate, anamine-terminated compound, and a curing agent.

Any hydroxy-terminated component is suitable for use as theisocyanate-reactive component to form a polyurethane using the one-shotmethod or a polyurethane prepolymer that is further reacted with acurative. The hydroxy-terminated component may be aromatic, aliphatic,or aromatic-aliphatic and may include primary hydroxy terminal groups,secondary hydroxy terminal groups, or a combination thereof.

For example, suitable hydroxy-terminated components include, but are notlimited to, polyether polyols, polycaprolactone polyols, polyesterpolyols, polycarbonate polyols, hydrocarbon polyols, and mixturesthereof. Suitable saturated polyether polyols for use in the presentinvention include, but are not limited to, polytetramethylene etherglycol (PTMEG); copolymer of polytetramethylene ether glycol and2-methyl-1,4-butane diol (PTG-L); poly(oxyethylene)glycol;poly(oxypropylene)glycol; poly(ethylene oxide cappedoxypropylene)glycol; and mixtures thereof.

Saturated polycaprolactone polyols include, but not limited to,diethylene glycol initiated polycaprolactone; propylene glycol initiatedpolycaprolactone; 1,4-butanediol initiated polycaprolactone; trimethylolpropane initiated polycaprolactone; neopentyl glycol initiatedpolycaprolactone; 1,6-hexanediol initiated polycaprolactone;polytetramethylene ether glycol (PTMEG) initiated polycaprolactone;ethylene glycol initiated polycaprolactone; dipropylene glycol initiatedpolycaprolactone; and mixtures thereof.

Suitable saturated polyester polyols include, but not limited to,polyethylene adipate glycol; polyethylene propylene adipate glycol;polybutylene adipate glycol; polyethylene butylene adipate glycol;polyhexamethylene adipate glycol; polyhexamethylene butylene adipateglycol; and mixtures thereof. An example of a polycarbonate polyol thatmay be used with the present invention includes, but is not limited to,poly(hexamethylene carbonate)glycol.

Hydrocarbon polyols include, but not limited to, hydroxy-terminatedliquid isoprene rubber (LIR), hydroxy-terminated polybutadiene polyol,saturated hydroxy-terminated hydrocarbon polyols, and mixtures thereof.Other aliphatic polyols that may be used to form the prepolymer of theinvention include, but not limited to, glycerols; castor oil and itsderivatives; Kraton polyols; acrylic polyols; acid functionalizedpolyols based on a carboxylic, sulfonic, or phosphoric acid group; dimeralcohols converted from the saturated dimerized fatty acid; and mixturesthereof.

When formed, polyurea or polyurethane prepolymers may contain about 10percent to about 20 percent by weight of the prepolymer of freeisocyanate monomer. Thus, in one embodiment, the prepolymer may bestripped of the free isocyanate monomer. For example, after stripping,the prepolymer may contain about 1 percent or less free isocyanatemonomer. In another embodiment, the prepolymer contains about 0.5percent by weight or less of free isocyanate monomer.

The prepolymers may be formed with a single curing agent or a blend ormixture of curing agents. For example, any curative that promotescrosslinking of the hard segments in the prepolymer may be used inaccordance with the present invention. In particular, the curing processinvolves the reaction of the prepolymer with an amine-terminated curingagent, a hydroxy-terminated curing agent, or a mixture thereof tocrosslink the hard segments, i.e., the isocyanate groups and the aminoand/or hydroxyl groups. In one embodiment, the curative includes atleast one amine-terminated curing agent. In another embodiment, thecurative includes at least one hydroxy-terminated curing agent. In yetanother embodiment, the curative is a blend of at least onehydroxy-terminated curing agent and at least one amine-terminated curingagent. Any of the amine-terminated components and hydroxy-terminatedcomponents described above for use as the isocyanate-reactive componentmay be used as a curative in accordance with the invention.

Other suitable amine-terminated curatives include, but are not limitedto, ethylene diamine; hexamethylene diamine; 1-methyl-2,6-cyclohexyldiamine; 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine;4,4′-bis-(sec-butylamino)-dicyclohexylmethane and derivatives thereof;1,4-bis-(sec-butylamino)-cyclohexane;1,2-bis-(sec-butylamino)-cyclohexane; 4,4′-dicyclohexylmethane diamine;1,4-cyclohexane-bis-(methylamine); 1,3-cyclohexane-bis-(methylamine),isomers, and mixtures thereof; diethylene glycol bis-(aminopropyl)ether;2-methylpentamethylene-diamine; diaminocyclohexane, isomers, andmixtures thereof; diethylene triamine; triethylene tetramine;tetraethylene pentamine; propylene diamine; 1,3-diaminopropane;dimethylamino propylamine; diethylamino propylamine;imido-bis-(propylamine); monoethanolamine, diethanolamine;triethanolamine; monoisopropanolamine, diisopropanolamine;isophoronediamine; 4,4′-methylenebis-(2-chloroaniline);3,5-dimethylthio-2,4-toluenediamine;3,5-dimethylthio-2,6-toluenediamine; 3,5-diethylthio-2,4-toluenediamine;3,5-diethylthio-2,6-toluenediamine; 3,5-diethyltoluene-2,4-diamine;3,5-diethyltoluene-2,6-diamine; 4,4′-bis-(sec-butylamino)-benzene; andderivatives thereof; 1,4-bis-(sec-butylamino)-benzene;1,2-bis-(sec-butylamino)-benzene; N,N′-dialkylamino-diphenylmethane;trimethyleneglycol-di-p-aminobenzoate;polytetramethyleneoxide-di-p-aminobenzoate;4,4′-methylenebis-(3-chloro-2,6-diethyleneaniline);4,4′-methylenebis-(2,6-diethylaniline); meta-phenylenediamine;paraphenylenediamine; N,N′-diisopropyl-isophoronediamine;polyoxypropylene diamine; propylene oxide-based triamine;3,3′-dimethyl-4,4′-ciaminocyclohexylmethane; and mixtures thereof. Inone embodiment, the amine-terminated curing agent is4,4′-bis-(sec-butylamino)-dicyclohexylmethane. The amine-terminatedcurative may have a molecular weight of about 64 or greater. In oneembodiment, the molecular weight of the amine-terminated curative isabout 2000 or less. It should be understood that molecular weight, asused herein, is the absolute weight average molecular weight and wouldbe understood as such by one of ordinary skill in the art.

Other suitable hydroxy-terminated curatives include, but are not limitedto, ethylene glycol; diethylene glycol; polyethylene glycol; propyleneglycol; 2-methyl-1,3-propanediol; 2,-methyl-1,4-butanediol; dipropyleneglycol; polypropylene glycol; 1,2-butanediol; 1,3-butanediol;1,4-butanediol; 2,3-butanediol; 2,3-dimethyl-2,3-butanediol;trimethylolpropane; cyclohexyldimethylol; triisopropanolamine;N,N,N′N′-tetra-(2-hydroxypropyl)-ethylene diamine; diethylene glycolbis-(aminopropyl)ether; 1,5-pentanediol; 1,6-hexanediol;1,3-bis-(2-hydroxyethoxy)cyclohexane; 1,4-cyclohexyldimethylol;1,3-bis-[2-(2-hydroxyethoxy)ethoxy]cyclohexane;1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}cyclohexane;polytetramethylene ether glycol, preferably having a molecular weightranging from about 250 to about 3900;resorcinol-di-(beta-hydroxyethyl)ether and its derivatives;hydroquinone-di-(beta-hydroxyethyl)ether and its derivatives;1,3-bis-(2-hydroxyethoxy)benzene;1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene;1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene;N,N-bis(.beta.-hydroxypropyl)aniline; 2-propanol-1,1′-phenylaminobis;and mixtures thereof.

The hydroxy-terminated curing agent may have a molecular weight of atleast about 50. In one embodiment, the molecular weight of thehydroxy-terminated curing agent is about 2000 or less. In yet anotherembodiment, the hydroxy-terminated curing agent has a molecular weightof about 250 to about 3900.

The curative may include a freezing point depressing agent to slow theonset of solidification. Examples of freezing point depressing agentssuitable for use in this aspect of the invention are disclosed in U.S.Patent Publication No. 2003/0212240, which is incorporated by referenceherein in its entirety. In one embodiment, the freezing point depressingagent includes, but is not limited to, ethylene diamine,1,3-diaminopropane, dimethylamino propylamine, tetraethylene pentamine,1,2-propylenediamine, diethylaminopropylamine,2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine,and mixtures thereof.

Golf Ball Core

The core of the present invention may be solid, semi-solid, hollow,fluid-filled or powder filled, one-piece or multi-component cores. Asused herein, the term “fluid” includes a liquid, a paste, a gel, a gas,or any combination thereof; the term “fluid-filled” includes hollowcenters or cores; and the term “semi-solid” refers to a paste, a gel, orthe like.

The core may have a diameter of about 1.5 inches to about 1.62 inches.The core compression preferably ranges from about 30 to about 120 attiand the overall ball compression is about 50 to about 115.

Any core material known to one of ordinary skill in the art is suitablefor use in the golf balls of the invention. In one embodiment, the coreis formed from a thermoset material, such as rubber, styrene butadiene,polybutadiene, isoprene, polyisoprene, trans-isoprene. For example,butadiene rubber, which, in an uncured state, typically has a Mooneyviscosity greater than about 20, preferably greater than about 30, andmore preferably greater than about 40, may be used in one or more corelayers of the golf balls prepared according to the present invention. Inanother embodiment, the core is formed from a thermoplastic material,such as ionomer resins, polyamides or polyesters, and mixtures thereof.In addition, the compositions of the present invention may beincorporated into the core.

Other materials preferred for the base polymer of the core includehigh-cis polybutadiene rubber that is cobalt-, nickel-, lithium-, orneodymium-catalyzed, most preferably Co- or Nd-catalyzed, having aMooney viscosity of about 25 to about 125, more preferably about 30 toabout 100, and most preferably about 40 to about 60. Lesser amounts ofnon-polybutadiene rubber, such as styrene butadiene rubber,trans-polyisoprene, natural rubber, butyl rubber, ethylene propylenerubber, ethylene propylene diene monomer rubber, low-cis polybutadienerubber, or trans polybutadiene rubber, may also be blended with thepolybutadiene rubber. A coagent, such as zinc diacrylate or zincdimethacrylate, is typically present at a level of about 0 pph to about60 pph, more preferably about 10 pph to about 55 pph, and mostpreferably about 15 pph to about 40 pph. A peroxide or peroxide blend isalso typically present at about 0.1 pph to about 5.0 pph, morepreferably about 0.5 pph to about 3.0 pph. Zinc oxide may also bepresent at about 5 pph to about 50 pph and the antioxidant is preferablypresent at about 0 pph to about 0.1 pph to about 5.0 pph, preferablyabout 0.5 pph to about 3.0 pph. Fillers may also be used to modify theweight of the core to create a specialty ball.

Layer Formation

The golf balls of the invention may be formed using a variety ofapplication techniques such as compression molding, flip molding,injection molding, retractable pin injection molding, reaction injectionmolding (RIM), liquid injection molding (LIM), casting, vacuum forming,powder coating, flow coating, spin coating, dipping, spraying, and thelike. Conventionally, compression molding and injection molding areapplied to thermoplastic materials, such as the compositions of theinvention, whereas RIM, liquid injection molding, and casting areemployed on thermoset materials. These and other manufacture methods aredisclosed in U.S. Pat. Nos. 6,207,784 and 5,484,870, the disclosures ofwhich are incorporated herein by reference in their entirety.

The cores of the invention may be formed by any suitable method known tothose of ordinary skill in art. When the cores are formed from athermoset material, compression molding is a particularly suitablemethod of forming the core. In a thermoplastic core embodiment, on theother hand, the cores may be injection molded.

The intermediate layer and/or cover layer may also be formed using anysuitable method known to those of ordinary skill in the art. Forexample, an intermediate layer may be formed by blow molding and coveredwith a dimpled cover layer formed by injection molding, compressionmolding, casting, vacuum forming, powder coating, and the like. in oneembodiment, the compositions of the invention are extruded with atwin-screw extruded, molded into half-shells, and compression moldedover a solid core as a casing layer. The cased balls may then be coveredwith a polyurethane or polyurea.

The use of various dimple patterns and profiles provides a relativelyeffective way to modify the aerodynamic characteristics of a golf ball.As such, the manner in which the dimples are arranged on the surface ofthe ball can be by any available method. For instance, the ball may havean icosahedron-based pattern, such as described in U.S. Pat. No.4,560,168, or an octahedral-based dimple patterns as described in U.S.Pat. No. 4,960,281. Furthermore, the resultant golf balls preparedaccording to the invention typically will have dimple coverage greaterthan about 60 percent, preferably greater than about 65 percent, andmore preferably greater than about 70 percent.

Golf Ball Post-Processing

The golf balls of the present invention may be painted, coated, orsurface treated for further benefits. For example, golf balls may becoated with urethanes, urethane hybrids, ureas, urea hybrids, epoxies,polyesters, acrylics, or combinations thereof in order to obtain anextremely smooth, tack-free surface. If desired, more than one coatinglayer can be used. The coating layer(s) may be applied by any suitablemethod known to those of ordinary skill in the art. In one embodiment,the coating layer(s) is applied to the golf ball cover by an in-moldcoating process, such as described in U.S. Pat. No. 5,849,168, which isincorporated in its entirety by reference herein.

Any of the golf ball layers may be surface treated by conventionalmethods including blasting, mechanical abrasion, corona discharge,plasma treatment, and the like, and combinations thereof. In fact,because low surface energy, or surface tension, is a key feature ofpolysiloxanes, layers formed from the compositions of the invention maybe surface treated according to U.S. Patent Publication No.2003/0199337, the disclosure of which is incorporated in its entirety byreference herein.

Golf Ball Properties

Properties such as core diameter, intermediate layer and cover layerthickness, hardness, and compression can also be altered to affect playcharacteristics such as spin, initial velocity and feel of the presentgolf balls.

Component Dimensions

Dimensions of golf ball components, i.e., thickness and diameter, mayvary depending on the desired properties. For the purposes of theinvention, any layer thickness may be employed. For example, the presentinvention relates to golf balls of any size, although the golf ballpreferably meets USGA standards of size and weight. While “The Rules ofGolf” by the USGA dictate specifications that limit the size of acompetition golf ball to more than 1.680 inches in diameter, golf ballsof any size can be used for leisure golf play. The preferred diameter ofthe golf balls is from about 1.680 inches to about 1.800 inches. Themore preferred diameter is from about 1.680 inches to about 1.760inches. A diameter of from about 1.680 inches (43 mm) to about 1.740inches (44 mm) is most preferred, however diameters anywhere in therange of from 1.700 to about 1.950 inches can be used. Preferably, theoverall diameter of the core and all intermediate layers is about 80percent to about 98 percent of the overall diameter of the finishedball. The core may have a diameter ranging from about 0.09 inches toabout 1.65 inches. In one embodiment, the diameter of the core of thepresent invention is about 1.2 inches to about 1.630 inches. Forexample, when part of a two-piece ball according to invention, the coremay have a diameter ranging from about 1.5 inches to about 1.62 inches.In another embodiment, the diameter of the core is about 1.3 inches toabout 1.6 inches, preferably from about 1.39 inches to about 1.6 inches,and more preferably from about 1.5 inches to about 1.6 inches. In yetanother embodiment, the core has a diameter of about 1.55 inches toabout 1.65 inches, preferably about 1.55 inches to about 1.60 inches. Inone embodiment, the core diameter is about 1.59 inches or greater. Inanother embodiment, the diameter of the core is about 1.64 inches orless.

The cover typically has a thickness to provide sufficient strength, goodperformance characteristics, and durability. In one embodiment, thecover thickness is from about 0.02 inches to about 0.12 inches,preferably about 0.1 inches or less. For example, when part of atwo-piece ball according to invention, the cover may have a thicknessranging from about 0.03 inches to about 0.09 inches. In anotherembodiment, the cover thickness is about 0.05 inches or less, preferablyfrom about 0.02 inches to about 0.05 inches, and more preferably about0.02 inches and about 0.045 inches.

The range of thicknesses for an intermediate layer of a golf ball islarge because of the vast possibilities when using an intermediatelayer, i.e., as an outer core layer, an inner cover layer, a woundlayer, a moisture/vapor barrier layer. When used in a golf ball of thepresent invention, the intermediate layer, or inner cover layer, mayhave a thickness about 0.3 inches or less. In one embodiment, thethickness of the intermediate layer is from about 0.002 inches to about0.1 inches, and preferably about 0.01 inches or greater. For example,when part of a three-piece ball or multi-layer ball according to theinvention, the intermediate layer and/or inner cover layer may have athickness ranging from about 0.015 inches to about 0.06 inches. Inanother embodiment, the intermediate layer thickness is about 0.05inches or less, more preferably about 0.01 inches to about 0.045 inches.

Spin Rate

A spin rate of a golf ball refers to the speed it spins on an axis whilein flight, measured in revolutions per minute (“rpm”). Spin generateslift, and accordingly, spin rate directly influences how high the ballflies and how quickly it stops after landing. The golf balls disclosedherein can be tested to determine spin rate by initially establishingtest conditions using suitable control golf balls and golf clubs. Forexample, a spin rate of a golf ball struck by a standard golf driver wasobtained by using test conditions for a Titleist NXT Tour® golf ballthat gives a ball speed of about 159 to about 161 miles/hour, a launchangle of about 9.0 degrees to about 10.0 degrees, and a spin rate ofabout 2900 rpm to about 3100 rpm. Thus, in one embodiment, the spin rateof a golf ball of the invention hit with a golf club driver under thesame test conditions is between about 1200 rpm to about 4200 rpm. In apreferred embodiment, the spin rate of a golf ball hit with a golf clubdriver is between about 2000 rpm to about 4000 rpm, more preferablybetween about 2500 and 3900 rpm.

For an 8-iron ball spin test, a spin rate of a golf ball struck by astandard 8-iron club was obtained by using test conditions for aTitleist NXT Tour® golf ball that gives a ball speed of about 114 toabout 116 miles/hour, a launch angle of about 18.5 to about 19.5 degreesand a spin rate of about 8350 rpm to about 8550 rpm. Thus, in oneembodiment, the spin rate of a golf ball with an average, cleanly struck8-iron shot is between 5500 rpm and 10,000 rpm. In preferred embodiment,the spin rate of a golf ball of the invention with an average, cleanlystruck 8-iron shot under the same test conditions is between 7500 rpmand 9500 rpm, more preferably between about 7700 rpm and 9300 rpm.

For a full wedge ball spin test, a spin rate of a golf ball struck by astandard full wedge was obtained by using test conditions for a TitleistNXT Tour® golf ball that gives a ball speed of about 93 to about 95miles/hour, a launch angle of about 24 to about 25 degrees and a spinrate of about 9650 rpm to about 9850 rpm. Thus, in one embodiment, thespin rate of a golf ball with an average, cleanly struck full wedge shotis between 8000 rpm and 12,000 rpm. In preferred embodiment, the spinrate of a golf ball of the invention with an average, cleanly struckfull wedge shot under the same test conditions is between 8500 rpm and11,500 rpm, more preferably between about 9000 rpm and 11,000 rpm.

For a half wedge ball spin test, a spin rate of a golf ball struck by astandard half wedge was obtained by using test conditions for a TitleistNXT Tour® golf ball that gives a ball speed of about 52 to about 54miles/hour, a launch angle of about 32 to about 34 degrees and a spinrate of about 5500 rpm to about 7500 rpm. Thus, in one embodiment, thespin rate of a golf ball with an average, cleanly struck half wedge shotis between 5000 rpm and 10,000 rpm. In preferred embodiment, the spinrate of a golf ball of the invention with an average, cleanly struckhalf wedge shot under the same test conditions is between 6200 rpm and8,500 rpm, more preferably between about 6500 rpm and 8000 rpm.

Hardness

Solid sphere cores formed of the compositions of the inventionpreferably have a hardness of greater than about 50 Shore D, morepreferably greater than about 60 Shore D, and even more preferablygreater than about 65 Shore D. For example, in one embodiment, a solidsphere formed of the composition of the invention has a hardness rangingfrom about 55 to about 62 Shore D.

As such, if additional golf ball layers are formed of the compositions,they also preferably have hardnesses in this range. For example, a golfball layer formed of the composition of the invention may have ahardness greater than about 55 Shore D. In one embodiment, the hardnessis about 60 Shore D or greater. In another embodiment, additional golfball layers are formed of alternative compositions with hardness rangesfrom about 35 Shore D to about 50 Shore D, preferably from about 40Shore D to about 50 Shore D. Because the compositions of the inventionmay be used in any layer of a golf ball, the golf ball construction,physical properties, and resulting performance may vary greatlydepending on the layer(s) of the ball that include the compositions ofthe invention.

The intermediate layer(s) of the present invention may also vary inhardness depending on the specific construction of the ball. In oneembodiment, the hardness of the intermediate layer is about 30 Shore Dor greater. In another embodiment, the hardness of the intermediatelayer is about 90 Shore D or less, preferably about 80 Shore D or less,and more preferably about 70 Shore D or less. For example, when anintermediate layer is formed from the compositions of the invention, thehardness of the intermediate layer may be about 55 Shore D or greater,preferably ranging from about 55 Shore D to about 65 Shore D. In yetanother embodiment, the hardness of the intermediate layer is about 50Shore D or less, preferably from about 35 Shore D to about 55 Shore D.The intermediate layer may also be about 65 Shore D or greater. Forexample, a golf ball of the invention may include an inner cover formedfrom a rosin-modified polymeric composition having a hardness of about60 Shore D to about 75 Shore D.

As with the core and intermediate layers, the cover hardness may varydepending on the construction and desired characteristics of the golfball. The ratio of cover hardness to inner ball hardness is a primaryvariable used to control the aerodynamics of a ball and, in particular,the spin of a ball. In general, the harder the inner ball, the greaterthe driver spin and the softer the cover, the greater the driver spin.

For example, when the intermediate layer is intended to be the hardestpoint in the ball, e.g., about 60 Shore D to about 75 Shore D, the covermaterial may have a hardness of about 20 Shore D or greater, preferablyabout 25 Shore D or greater, and more preferably about 30 Shore D orgreater, as measured on the slab. In another embodiment, the coveritself has a hardness of about 30 Shore D or greater. In particular, thecover may be from about 30 Shore D to about 70 Shore D. In oneembodiment, the cover has a hardness of about 40 Shore D to about 65Shore D, and in another embodiment, about 40 Shore to about 55 Shore D.In another aspect of the invention, the cover has a hardness less thanabout 45 Shore D, preferably less than about 40 Shore D, and morepreferably about 25 Shore D to about 40 Shore D. In one embodiment, thecover has a hardness from about 30 Shore D to about 40 Shore D.

Compression

Compression is an important factor in golf ball design. For example, thecompression of the core can affect the spin rate of the ball off thedriver, as well as the feel of the ball when struck with the club. Asdisclosed in Jeff Dalton's Compression by Any Other Name, Science andGolf IV, Proceedings of the World Scientific Congress of Golf (EricThain ed., Routledge, 2002) (“J. Dalton”), several different methods canbe used to measure compression, including Atti compression, Riehlecompression, load/deflection measurements at a variety of fixed loadsand offsets, and effective modulus. For purposes of the presentinvention, “compression” refers to Atti compression and is measuredaccording to a known procedure, using an Atti compression test device,wherein a piston is used to compress a ball against a spring. The travelof the piston is fixed and the deflection of the spring is measured. Themeasurement of the deflection of the spring does not begin with itscontact with the ball; rather, there is an offset of approximately thefirst 1.25 mm (0.05 inches) of the spring's deflection. Very lowstiffness cores will not cause the spring to deflect by more than 1.25mm and therefore have a zero compression measurement. The Atticompression tester is designed to measure objects having a diameter of42.7 mm (1.68 inches); thus, smaller objects, such as golf ball cores,must be shimmed to a total height of 42.7 mm to obtain an accuratereading. Conversion from Atti compression to Riehle (cores), Riehle(balls), 100 kg deflection, 130-10 kg deflection or effective moduluscan be carried out according to the formulas given in J. Dalton.

As known to those of ordinary skill in the art, compression values aredependent on the diameter of the component being measured. The Atticompression of the core, or portion of the core, of golf balls preparedaccording to the invention may range from about 30 to about 110 atti,preferably about 50 to about 100 atti. In one embodiment, the corecompression is less than about 80, preferably less than about 75. Inanother embodiment, the core compression is from about 40 to about 80,preferably from about 50 to about 70. In yet another embodiment, thecore compression is preferably below about 50, and more preferably belowabout 25.

In an alternative, low compression embodiment, the core has acompression less than about 20, more preferably less than about 10, andmost preferably, 0. As known to those of ordinary skill in the art,however, the cores generated according to the present invention may bebelow the measurement of the Atti Compression Gauge.

In one embodiment, golf balls of the invention preferably have an Atticompression of about 55 or greater, preferably from about 60 to about120. In another embodiment, the Atti compression of the golf balls ofthe invention is at least about 40, preferably from about 50 to 120, andmore preferably from about 50 to 100. In yet another embodiment, thecompression of the golf balls of the invention is about 75 or greaterand about 95 or less. For example, a preferred golf ball of theinvention may have a compression from about 80 to about 95.

Coefficient of Restitution

The coefficient of restitution or COR of a golf ball is a measure of theamount of energy lost when 2 objects collide. The COR of a golf ballindicates its ability to rebound and accounts for the spring-like feelof the ball after striking. The present invention contemplates golfballs having CORs from about 0.700 to about 0.850 at an inbound velocityof about 125 ft/sec. In one embodiment, the COR is about 0.750 orgreater, preferably about 0.780 or greater. In another embodiment, theball has a COR of about 0.800 or greater. In yet another embodiment, theCOR of the balls of the invention is about 0.800 to about 0.815.

Solid spheres (1.54 inches) formed of the compositions of the inventionmay have a COR of at least about 0.700, preferably at least about 0.710.For example, the COR of solid spheres formed from the compositions ofthe invention ranges from about 0.710 to about 0.760. In one embodiment,a solid sphere formed from the composition of the invention has a COR ofabout 0.740 to about 0.760.

Alternatively, the maximum COR of the ball is one that does not causethe golf ball to exceed initial velocity requirements established byregulating entities such as the USGA. As used herein, the term“coefficient of restitution” (CoR) is calculated by dividing the reboundvelocity of the golf ball by the incoming velocity when a golf ball isshot out of an air cannon at a steel plate. The COR is calculated bydividing the rebound velocity of the golf ball by the incoming velocity.Thus, a ball with a high coefficient of restitution dissipates a smallerfraction of its total energy when colliding with the plate andrebounding therefrom than does a ball with a low coefficient ofrestitution. The COR testing is conducted over a range of incomingvelocities and determined at an inbound velocity of 125 ft/s. Anothermeasure of this resilience is the “loss tangent,” or tan δ, which isobtained when measuring the dynamic stiffness of an object. Loss tangentand terminology relating to such dynamic properties is typicallydescribed according to ASTM D4092-90. Thus, a lower loss tangentindicates a higher resiliency, thereby indicating a higher reboundcapacity. Low loss tangent indicates that most of the energy imparted toa golf ball from the club is converted to dynamic energy, i.e., launchvelocity and resulting longer distance. The rigidity or compressivestiffness of a golf ball may be measured, for example, by the dynamicstiffness. A higher dynamic stiffness indicates a higher compressivestiffness. To produce golf balls having a desirable compressivestiffness, the dynamic stiffness of the crosslinked material should beless than about 50,000 N/m at −50° C. Preferably, the dynamic stiffnessshould be between about 10,000 and 40,000 N/m at −50° C., morepreferably, the dynamic stiffness should be between about 20,000 and30,000 N/m at −50° C.

EXAMPLES

The following non-limiting examples are merely illustrative of thepreferred embodiments of the present invention, and are not to beconstrued as limiting the invention, the scope of which is defined bythe appended claims. Parts are by weight unless otherwise indicated.

Example 1 Compositions of the Invention

Tests were performed to compare the properties of a golf ballscontaining a casing layer formed of the present invention. The polymerblends used for testing are listed in Table 1. Examples 1, 3, and 5 arehigh acid ionomer—maleic anhydride grafted metallocene catalyzed polymerblends with standard ionomer melt flow modifiers. Examples 2, 4, and 6are representative compositions of the invention including a high acidionomer—maleic anhydride grafted metallocene catalyzed polymer blendwith high acid melt flow modifiers. Components are included in pphunless other noted.

TABLE 1 Components Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Control Surlyn ®8140¹ 80.0 72.0 64.0 Fusabond ® 572D² 16.0 16.0 24.4 24.4 33.0 33.0 HighAcid 80.0 72.0 64.0 Ionomer³ Nucrel ® 960⁴ 4.0 3.6 3.0 Melt Flow 4.0 3.63.0 Modifier⁵ Surlyn ® 7940 50.0 Surlyn ® 8940 50.0 ¹Surlyn ® 8140 is anethylene-based ionomer believed to include about 17 weight percent toabout 20 weight percent methacrylic acid with acid groups neutralizedwith sodium (commercially available from DuPont) with an MFI of 2.6 g/10min. ²Fusabond ® 572D is a metallocene-catalyzed ethylene-butenecopolymer grafted with 0.9 percent maleic anhydride and having a 4.0MFI. ³High Acid Ionomer is an ethylene-acrylic acid copolymer with 17percent acid groups, where a portion of the acid groups are partiallyneutralized with sodium about 30 percent to about 50 percent, with a 2.6MFI. ⁴Nucrel ® 960 is an ethylene-acrylic acid copolymer with 15 percentacid groups having an MFI of 60 g/10 min. ⁵Flow Modifier is anethylene-acrylic acid copolymer with 17 percent acid groups having anMFI of 60 g/10 min.

Each of the compositions listed above, with the exception of theControl, were made by carrying out reactive extrusion of the ionomericcomponent with a maleic anhydride grafted ethylene-butene metallocenecopolymer in a twin-screw extruder.

Table 2 illustrates the flex-bar properties of each of the compositions.

TABLE 2 Test Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Control FlexuralModulus 60.1 55.7 52.2 51.8 41.7 41.8 65.8 (kpsi) Hardness (Shore D)57.0 56.8 54.6 55.5 50.7 52.6 62.1 Hardness (Shore C) 88.8 88.7 86.287.8 82.4 83.7 91.0

Example 2 Cased Balls

The composition described in Example 1 were then molded into half-shellsand compression molded into casing layers over polybutadiene cores. Theresults are shown in Table 3.

TABLE 3 Test Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Control AverageDiameter (inches) 1.623 1.623 1.624 1.623 1.624 1.623 1.622 Compression(atti) 86.6 85.7 85.4 84.8 84.3 83.5 87.7 Weight (oz.) 1.46 1.46 1.461.46 1.46 1.46 1.45 Hardness (Shore D) 58.5 58.8 55.6 55.3 52.5 52.362.7 Hardness (Shore C) 88.7 87.4 83.9 84.0 80.6 80.3 89.7 PerformanceTesting at 1 week CoR @ 125 ft/sec .0805 0.805 0.803 0.803 0.801 0.8000.807 Air Cannon Durability Testing Number of Hits to 1^(st) Failure 121191 210 198 265 311 151 Number of Hits to 50% Failure 225 244 342 235NR* NR 197 Number of Hits to 100% Failure 334 393 NR 319 NR NR 257*Failure level not reached.

Example 3 Solid Spheres Formed from the Compositions of the Invention

The compositions from Table 1 were also formed into solid spheres (1.550inches). The results of these tests are shown in Table 4.

TABLE 4 Test Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Control AverageDiameter (inches) 1.54 1.54 1.54 1.54 1.54 1.54 1.54 Compression (atti)51.7 51.2 50.8 46.0 40.8 36.0 58.3 Hardness (Shore D) 62.7 62.2 60.459.9 57.0 56.1 66.9 Hardness (Shore C) 93.6 93.5 92.4 92.1 88.1 87.496.1 Performance Testing at 1 week CoR@125 ft/sec 0.743 0.759 0.7350.748 0.716 0.734 0.754

Example 4 Polyurea-Covered Golf Balls of the Invention

Cased balls formed according to Example 2 were covered with a polyureamaterial and performance tested. Table 5 shows the results of thesetests.

TABLE 5 Test Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Control AverageDiameter   1.684   1.684 1.6831   1.683 1.683 1.683 1.683 (inches)Compression (atti)  93.9  93.7 92.5  91.6 90.3 89.6 94.8 Weight (oz.)  1.619   1.619 1.615   1.615 1.611 1.613 1.616 Hardness (Shore D)  57.1 57.0 55.4  55.3 54.2 53.3 58.5 Hardness (Shore C)  79.8  80.9 81.1 81.1 80.3 79.5 80.7 Performance Testing CoR@125 ft/sec   0.800   0.8010.798   0.797 0.795 0.795 0.799 Cold-Crack Test No No No No No No No (5°F./one hit per day Failures Failures Failures Failures Failures FailuresFailures for 15 days) Spin Rate from 8- 8419 8398 8641 8601 8886 88688306 Iron (rpm) Launch Angle  18.9°  18.9° 18.7°  18.7° 18.5° 18.4°19.0° Spin-Rate from ½ 7116 7099 7195 7158 7344 7332 7024 Wedge (rpm)Launch Angle  31°  31° 30.9°  31° 30.6° 30.7° 31.1°

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Furthermore, when numerical ranges ofvarying scope are set forth herein, it is contemplated that anycombination of these values inclusive of the recited values may be used.

All patents and patent applications cited in the foregoing text areexpressly incorporate herein by reference in their entirety. Theinvention described and claimed herein is not to be limited in scope bythe specific embodiments herein disclosed, since these embodiments areintended as illustrations of several aspects of the invention. Anyequivalent embodiments are intended to be within the scope of thisinvention. Indeed, various modifications of the invention in addition tothose shown and described herein will become apparent to those skilledin the art from the foregoing description. Such modifications are alsointended to fall within the scope of the appended claims.

1. A golf ball comprising: a core; a casing layer disposed about thecore, wherein the casing layer comprises a blend comprising: a high acidionomer comprising greater than about 16 percent acid groups by weightof the high acid ionomer, wherein between about 25 percent and about 70percent of the acid groups are neutralized with a metal cation, ametallocene catalyzed polymer comprising at least one grafted moiety;and an unneutralized acid copolymer comprising about 17 percent to about30 percent acid groups by weight of the unneutralized acid copolymer;and a cover having a hardness of about 30 to about 55 Shore D andcomprising a composition formed from a polyurethane prepolymer and ahydroxy-terminated curing agent, wherein the polyurethane prepolymercomprises the reaction product of an isocyanate and a hydroxy-terminatedcomponent.
 2. The golf ball of claim 1, wherein the at least one graftedmoiety is selected from the group consisting of maleic anhydride,fumaric anhydride or itaconic anhydride.
 3. The golf ball of claim 1,wherein the high acid ionomer is present in the blend in an amount ofabout 84 pph to about 67 pph based on the total blend.
 4. The golf ballof claim 3, wherein the blend comprises about 10 to about 40 pph of themetallocene catalyzed polymer based on the total blend.
 5. The golf ballof claim 4, wherein the blend comprises between about 2 and 4 pph of theunneutralized acid copolymer based on the total blend.
 6. The golf ballof claim 1, wherein between about 30 and 60 percent of the acid groupsare neutralized in the high acid ionomer.
 7. The golf ball of claim 1,wherein the core comprises polybutadiene.
 8. The golf ball of claim 1,wherein the metallocene catalyzed polymer comprises a copolymer ofethylene and butene.
 9. The golf ball of claim 8, wherein themetallocene catalyzed polymer comprises maleic anhydride graftedmetallocene catalyzed polymer.
 10. The golf ball of claim 1, wherein theunneutralized acid copolymer has a melt flow index of
 60. 11. A golfball comprising: a core; a casing layer disposed about the core, whereinthe casing layer comprises a blend comprising: a high acid ionomercomprising greater than about 16 percent acid groups by weight of thehigh acid ionomer, wherein between about 25 percent and about 70 percentof the acid groups are neutralized with a metal cation; and ametallocene catalyzed polymer comprising at least one grafted moiety;and an unneutralized acid copolymer comprising greater than 16 percentacid groups by weight of the unneutralized acid copolymer; a covercomprising a composition formed from a polyurethane prepolymer and ahydroxy-terminated curing agent, wherein the polyurethane prepolymercomprises the reaction product of an isocyanate and a hydroxy-terminatedcomponent.
 12. The golf ball of claim 10, wherein the unneutralized acidcopolymer is present in the blend in an amount between about 2 and 4 pphbased on the total blend.
 13. The golf ball of claim 10, wherein betweenabout 30 percent and about 60 percent of the acid groups in the highacid ionomer are neutralized.
 14. The golf ball of claim 10, wherein theat least one grafted moiety comprises maleic anhydride.
 15. The golfball of claim 10, wherein the core comprises polybutadiene.
 16. The golfball of claim 10, wherein the high acid ionomer is present in the blendin an amount ranging from about 84 to about 67 pph based on the totalblend.
 17. The golf ball of claim 16, wherein the metallocene catalyzedpolymer is present in the blend in an amount ranging from about 16 toabout 33 pph based on the total blend.
 18. The golf ball of claim 11,wherein the unneutralized acid copolymer has a melt flow index of 60.19. A golf ball comprising: a core; a casing layer disposed about thecore, wherein the casing layer comprises a blend comprising: a high acidionomer comprising between about 17 and 25 percent acid groups by weightof the high acid ionomer, wherein between about 30 percent and about 60percent of the acid groups are neutralized with a metal cation; and ametallocene catalyzed polymer having the following general formula:

wherein R₇ comprises a hydrogen, a linear or branched alkyl group, anaromatic or heterocyclic group, or a combination thereof; R₈, R₉, R₁₁,and R₁₂ comprises a hydrogen, a lower alkyl group comprising 1 to 5carbon atoms, a carbocyclic group, an aromatic or heterocyclic group, ora combination thereof; and x, y, and z are the relative percentages ofeach co-monomer, wherein x ranges from 1 percent to 99 percent, y rangesfrom 99 percent to 1 percent, and z ranges from 0 percent to 49 percent;and an unneutralized acid copolymer comprising greater than 16 percentacid groups by weight of the melt flow modifier; a cover comprising acomposition formed from a polyurethane prepolymer and ahydroxy-terminated curing agent, wherein the polyurethane prepolymercomprises the reaction product of an isocyanate and a hydroxy-terminatedcomponent.
 20. The golf ball of claim 19, wherein the unneutralized acidcopolymer has a melt flow index of 60.